Kuraray Noritake Dental Developed New Flexible Zirconia

  Kuraray Noritake Dental Developed New Flexible Zirconia

 A world first! Combining high strength, superior toughness and hydrothermal
                                  resistance
               Expanding into dental materials and other fields

Business Wire

TOKYO -- June 3, 2014

Kuraray Noritake Dental Inc., a joint venture of Kuraray Co., Ltd.
(TOKYO:3405) and Noritake Co., Limited (TOKYO:5331), has developed a highly
durable zirconia that possesses both high strength and superior toughness.
Kuraray Noritake Dental is pursuing the marketing of this new and unique
product in the dental material and other fields.

The photo shows a side view of a 0.2 mm thickness by 4.0 mm width plate of the
new product being sub ...

The photo shows a side view of a 0.2 mm thickness by 4.0 mm width plate of the
new product being subjected to a three-point flexural strength test. (Photo:
Business Wire)

1. Characteristics of the Material

Kuraray Noritake Dental developed the new durable zirconia, improving the raw
materials and manufacturing processes, aiming to develop a highly reliable
ceramic material. Kuraray Noritake Dental succeeded in developing a new type
of zirconia that has both higher flexural strength and fracture toughness^1
and, when exposed to hydrothermal condition, its crystal structure does not
change to a monoclinic phase, a common cause of compromised strength. In
addition, the product does not need to be subjected to Hot Isostatic Pressing.

The yttria partially stabilized zirconia currently in wide use is very strong,
however, it possesses the fragility which is characteristic of ceramics.
Zirconia is also known to gradually weaken over time as the crystal structure
changes from a tetragonal phase to a monoclinic one when exposed to
hydrothermal condition^2.

                                                                 
Comparison with Existing Products                                 
Examined Property       Unit                      Conventional   New Product
                                                    Zirconia
Three-point flexural     MPa (megapascal)           900–1,200      1,500
strength
                         MPa√m (megapascal square
Fracture toughness       root                       4–5            12
                         meter)
Ratio of
monoclinic phase        % (percent)               80            <1
(accelerated aging
test)
The above based on comparative data obtained by Kuraray Noritake Dental.


Since the new product has higher flexural strength and fracture toughness than
conventional zirconia, it exhibits such characteristics as the ability to
withstand being deformed to a high degree without fracturing.

The conventional zirconia fractured at the 4 mm mark compared with the
starting horizontal position. The new product, however, maintained its
integrity until it was pressed into a 6 mm arc, confirming its high fracture
toughness.

2. Potential Applications

Mainly dental materials, prosthetic joints and general industrial
applications.

About Kuraray Noritake Dental

Kuraray Noritake Dental Inc. was launched with the integration of Kuraray
Medical Inc. and Noritake Dental Supply Co., Ltd. in 2012. The two companies,
both of which have enjoyed the leading market share in Japan for the advanced
technological capabilities in their respective business fields (resin based
dental materials and dental ceramics), decided to join forces with an eye to
making even greater strides in expanding their domains and creating new fields
in the future.

Note to editors:
1. Resistance to extending cracks: higher number means more difficult to break
2. Tested under ISO 13356:2008

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Contact:

Kuraray Co., Ltd.
Takeshi Hasegawa, +81-3-6701-1080
kuraraykoho@kuraray.co.jp
 
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